Nickel electroplating composition



Nickel plating baths Patented Sept. 9, 1947 2,427,280 NICKEL ELECTROPLATING COMPOSITION Raymond A. Hoffman, Euclid, Ohio, assignor to E. I. du Pont de Nem ours & Company, Wilmington, Del., a corporation of Delaware Serial No.

2 Claims.

This invention relates to nickel plating and is more particularly directed to nickel plating processes and compositions wherein there is used as an addition agent an aliphatic sulfonic acid having a cyclic substituent.

Nickel plating baths have heretofore been modified by the inclusion of sulfonic acids or sulfation products of various organic compounds. containing such addition agents are of improved character but much is still left to be desired. While the prior art addition agents have usually effected some improvement in the character of deposit the agents individually are not sufficient to produce commercially desirable deposits and they must be used with another and sometimes with even two or more supplemental addition agents. Sometimes the addition agents while improving nickel deposits with respect to one characteristic, say brightness, are actually deleterious as to other essential characteristics such as ductility and freedom from pits. Either alone or'in combination with other addition agents these sulfation and sulfonation products have not been all that could be desired.

It is an object of the present invention to provide nickel plating compositions and processes of improved character. It is a further object of the present invention to provide nickel plating compositions and processes by means of which ductile nickel deposits may be obtained. It is a still further object to provide nickel plating compositions and processes by means of which there may be produced bright and ductile nickel deposits. It is a still further object to provide nickel plating compositions and processes which will provide a nickel deposit of good character over a wide range of current densities. It is a still further object to provide addition agents which will benefit nickel plating compositions and processes and the nickel deposits obtainable therewith. It is a still further object to provide an addition agent particularly applicable for the improvement of nickel chloride plating compositions and processes and the deposits obtainable therewith. It is a still further object to provide addition agents which may advantageously be used in nickel plating compositions and processes as a sole addition agent or which may advantageously be used with other addition agents. Still further objects will become apparent hereinafter.

The foregoing and other objects of this invention are attained by using as an addition agent for nickel plating baths an aliphatic sul- No Drawing. Application February 11, 1941,

ionic acid having .a cyclic substituent. use of these addition agents deposits of excellent character are produced. These deposits are ductile and bright. The addition agents do not promote pitting and they increase the range of current densities over which deposits of good character can be produced. Not only are the addition agents markedly beneficial when used alone, but they possess an unusual capability for being used in combination with other addition agents known to the art to produce joint efiects greater than would be expected from a consideration of the attributes of the individual agents.

Aliphatic sulfonic acids having a cyclic substituent may have as a substituent on the allphatic group any aromatic or cycloaliphatic radical may be carbocyclic or heterocyclic and the heterocyclic radical may have as the heteroatom such elements as oxygen, sulfur, and nitrogen. More specifically, there may be mentioned phenyl-substituted alkyl sulfonic acids, furylsubstituted alkyl sulfonic acids, cyclopentyl-substituted alkyl sulfonic acids, and naphthyl-substituted alkyl sulfonic acids. The aliphatic group may contain one or more sulfonic acid groups and these may be located on the same or different carbon atoms. It is generally preferable for the aliphatic to be a hydrocarbon group and for the aromatic substituent to be a hydrocarbon group except for the hetero-atom if any. The addition agent should be at least slightly bath soluble.

As typical aliphatic sulfonic acids with a cyclic substituent the following are given:

H H C=C S 0 3H 2-phenyl ethylene sulfonic acid 7 H H C-CSOzH 2-hydroxy-2-phenyl ethane sulionic acid 2-phenyl ethane sulionlc acid By the Z-phenyl ethane-1,1-disulfonic acid SOIH ii-Phenyl propylene-2sulionic acid 3-phenyl propionaldehyde-2-sulionic acid 3-pi1enyl propionic acid-2-sulfonic acid Q Ada (l-methyl-l-sulio)-3-ethylene-G-methoxybenzene Ag AOsH (l-methyll-sull'o)-3-ethylene-5,6-mcthylene-dioxybenzene SOaH 90 CHI H (i-mcthyl-l-sulfo)-3-ethylene-5-methoxy-6-hydroxy-benzene 2-iuryl ethane sulionic acid 50311 H: J] O- H Z-furyl ethane-1,1-disu1fonic acid 2-iuryl propionaldehyde-l-sulionic acid SQaH 2-iuryl propionaIdehyde-l-mcthyl-l-sulfonic acid ethylene-S-cyclopentyl-l-sulfonic acid H: HaC-C 20. 1,2-dipheny1 ethylene sulionic acid.

It will be understood that while reference is made herein to .sulfonic acids this term as is customary in the art is used to refer to either the free acid or to a bath-soluble salt. It is immaterial for purposes of this invention whether the free sulfonic acids are used or whether they are used in the form of bath-soluble salts since in any case the actual compound contained in the bath will depend upon the alkalinity or acidity. This practice is particularly mentioned in the Lutz-Westbrook Patent 1,818,229, just before the claims.

The amount of an aliphatic sulfonic acid having a cyclic substituent to use will depend upon the particular bath and upon the particular effect desired. In general, from about one to twenty grams per liter of such an addition agent may advantageously be used. The best results were obtained in a sulfate-nickel plating bath with about two to four grams per liter of an aliphatic sulfonic acid havinga cyclic substituent while in a chloride-nickel bath five to seven grams per liter was optimum. It will be understood that in either case larger or smaller amounts may advantageously be used but the specific ranges mentioned, under the particular conditions of bath operation, led to deposits of desired ductility and brilliance.

When the addition agents of the present invention are used in conjunction with another brightening agent the amount of addition agent is ordinarily reduced by at least fifty per cent and the brightness of deposit is usually increased over that obtained with either brightener alone. In any event the amount of addition agent to u e in any particular instance can best be determined by taking a small quantity of the particular bath to be improved and trying various is M small quantities of the addition agent until the desired results are obtained. The amount can easily be determined by a few simple tests with the standard test cells now in common use by electroplaters for this purpose.

The addition agents of the present invention may advantageously be used with any of the addition agents known to the art of which those heretofore listed as shown in the Lutz-Westbrook, Schlotter, Waite, Pine, Harshaw, and Flett patents are typical. The so-called metal brighteners such as zinc or cadmium may also be used if desired and it may sometimes be found desirable to use sulfated higher alcohols. The addition agents of this invention may be used to advantage with a benzaldehyde having an oxyacid substituent on the benzene ring such as meta-sulfobenzaldehyde or orthosulfobenzaldehyde.

While certain nickel plating baths are shown herein, it will be understood that the addition agents of this invention may advantageously be used in any nickel plating bath. The baths shown in the previously mentioned patents to Lutz-Westbrook, Schlotter, Waite, Pine, Harshaw, and Flett as well as those of the Lind- Harshaw-Long Patents 2,198,267 and 2,198,268 may advantageously be used.

The addition agents of the present invention have particularly great merit in chloride-nickel plating baths of a type recently developed. Such chloride-nickel plating baths are illustrated hereinatter in the examples, see for instance Example II, and they are characterized by containing chloride anion and sulfate anion in the ratio of :1 to 20: 1 on the basis of molecular equivalents. In other words, the ratio Nickel plating compositions according to the present invention may be offered to the trade as mixtures including suitable nickel compounds and a suitable aliphatic sulfonic acid having a cyclic substituent, the proportions of materials being such as to give upon solution in water a proper proportion of bath constituent. The allphatic sulfonic acid having a cyclic substituent may of course be present either as the sulfonic acid or as a bath-soluble salt such as a sodium, potassium, amine, or nickel salt. The compositions as sold may contain any further addition agent which it is desired to use and it may sometimes be found desirable to sell mixtures of addition agents for inclusion in baths already made up. It will be understood that the term nickel plating composition is used herein in the customary way to refer to a packaged dry mixture as offered to the trade, to 'a. concentrated solution suitable upon dilution for use as a plating bath either with or without the addition of fur. ther materials, and to the baths themselves.

As aliphatic sulfonic acids having a cyclic substituent which have been tested in plating baths with particularly interesting results I may mention 2-phenyl ethylene sulfonic acid, 2-hydroxy- 2-phenyl ethane sulfonic acid, 2-phenyl ethane sulfonic acid, 2-phenyl ethane-Ll-disulfonic acid, 3-phenyl propionaldehyde-2-sulfonie acid, 2-furyi propionaldehyde-l-sulfonic acid, and 2- furyl prcpionaldehyde-l-methyl-l-sulfonic acid. The practice of my invention may be better understood by reference to the following illustrative examples:

' Example I A nickel plating bath according to the present invention was made up as follows:

Nickel sulfate (NlSOr'II-IQO') grams per liter 350 r n ing from five to eighty amperes per square foot and gave beautiful nickel deposits which were bright, lustrous, and ductile.

The aliphatic sulfonic acid having a cyclic substituent which was used as an addition agent according to this example was prepared by treating styrene with sulfamic acid to form the amine salt of the sulfonic acid. The addition agent was used as the salt. Addition agents other than the 2-pheny1 ethylene sulfonic acid may also be prepared by a similar reaction using apiol, safrol, anethol, eugenol, vinyl naphthalene, or other organiccompounds having an unsaturated structure in the side chain for reaction with sulfamic acid to form the corresponding unsaturated sulfonic acid.

Example II A preferred chloride-nickel plating bath of th invention was made up as follows:

Nickel chloride (NiCl2-6H2O) grams per liter 250 Nickel sulfate (NiSOr'lHaO) do 15 Boric acid (HsBOa) do 50 z-phenyl ethylene sulfonic acid do 5 Temperature C 55 pH 3.5

Bright nickel deposits of excellent character were obtained from the bath of this example.

Example III A plating bath according to the present invention was prepared using two addition agents as in the following:

Nickel sulfate (NiSO4'7H2O) grams per liter 350 Excellent bright nickel deposits were obtained from this bath.

Example IV A chloride-nickel bath was made up with two addition agents as follows:

Brilliant nickel deposits of excellent character were obtained over a wide range of current densi- 7 ties, five, to eighty-five amperes per square foot, using this bath.

Example V A chloride-nickel plating bath of this invention was made up using a different aliphatic sulfonic acid having a cyclic substituent as follows:

Nickel chloride (NiCl2-6HzO) grams per liter 250 Nickel sulfate (NiSO4-7H2O) do 15 Boric acid (HaBOs) do 50 Z-furylpropionaldehyde-l-methyl-lsulfonic acid do 4 Temperature C 55 Deposits from this bath were ductile, bright, and of very fluid character. Bright deposits were obtained from about five to sixty amperes Per square foot.

Example VI A sulfate-nickel bath of the invention was made up as follows:

Nickel sulfate (NiSO4-7H2O) grams per liter 350 Nickel chloride (NiC12-6H2O) do.. 15

Boric acid (HsBOa) do 35 2-hydroxy-2-phenyl ethane sulfonic acid grams per liter 3 Temperature C 50 Smooth, pit-free, ductile deposits were obtained.

Example VII Still another sulfate-nickel bath illustrative of the invention was made up as follows:

Nickel sulfate (NiSO4-7HzO) rams per liter 350 Nickel chloride (NiClz-SHzO) do 15 Boric acid (HaBOa) do 35 2-phenyl ethane sulfonic acid do 2 Temperature C 50 pH 3.5

Bright, ductile deposits were obtained over the entire plating range.

Example VIII A still further sulfate-nickel bath of the present invention was made up as follows:

Nickel sulfate (NiSO4-7HzO) grams per liter 350 Nickel chloride (NiCl2-6H2O) d 15 Boric acid (H3303) do 35 2-phenyl ethane-Ll-disulfonic acid do 2 Temperature C 50 pH 3.5

Bright, ductile deposits were obtained over the entire plating range.

Example IX A still further sulfate-nickel bath illustrative of the present invention was made up as follows:

Nickel sulfate (NiSO4-7H2O) Nickel chloride (NiClz-6Hz0) do Boric acid (HaBOs) do grams per liter 350 3-phenylpropionaldehyde-Z-sulfonic acid do 5 Temperature C 50 pH 3.5

Bright, ductile deposits were obtained over the entire plating range.

Example X A still further sulfate-nickel .bath illustrative of the invention was made up as follows:

Nickel sulfate (Ni SO'4'7H2O) grams per liter 350 Nickel chloride (NiCl2 6H2O) l do 15 Boric acid (H3BO3) do 35 2-furylpropionaldehyde-l-sulfonic acid d0 5 Temperature C 50 Bright, ductile deposits were obtained over the entire plating range.

, Example XI A still further chloride-nickel bath illustrative of the invention was made up as follows:

Nickel chloride (NiC12-6H20) grams per liter 250 Nickel sulfate (NlsOl'7H20) do w 15 Boric acid (H3303) do 50 2-furylpropionaldehyde-l-sulfonic acid do 7 the l. A nickel plating composition for dissolvingin water to make an aqueous plating bath comprising nickel chloride, nickel sulfate, and 2-phenyl ethylene sulfonic acid,

2. In a process for the deposition of nickel, the step comprising depositing nickel from an aqueous bath in the presence of 2-phenyl ethylene sulfonic acid.

RAYMOND A. HOFFMAN.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,029,387 Pine Feb. 4, 1936 2,312,097 Hull et al Feb. 23, 1943 OTHER REFERENCES Chemistry of Pulp and Paper Making-Sutermeister, 2d' edition, (1929), published by John Wiley and Sons Inc., New York, page 182.

Wood Chemistry-Wise, published in 1944 by Reinhold Publishing 00., page 337.

Certificate of Correction Patent No. 2,427,280.

RAYMOND A. HOFFMAN It is hereby certified that error appears in the printed specification of the above numbered patent requiring correction as follows: Column 2, line 17, after radical insert a period and words The aromatic radzcal; and that the said Letters Patent should be read with this correction therein that the same may conform to the record of the case in the Patent Office.

Signed and sealed this 25th day of November, A. D. 1947.

THOMAS F. MURPHY,

Assistant Commissioner of Patents.

September 9, 1947. 

